And here is one more patch to test the same idea (chip->retrigger()).
Let's try i386 way! (I hope I will not be arrested for this...)
(Should be tested without any previous patches.)

Jarek P.

PS: as above

---

diff -Nurp 2.6.22.1-/arch/x86_64/kernel/io_apic.c 2.6.22.1/arch/x86_64/kernel/io_apic.c

--- 2.6.22.1-/arch/x86_64/kernel/io_apic.c      2007-07-09 01:32:17.000000000 +0200
+++ 2.6.22.1/arch/x86_64/kernel/io_apic.c       2007-08-07 14:37:45.000000000 +0200

@@ -1311,15 +1311,8 @@ static unsigned int startup_ioapic_irq(u
 static int ioapic_retrigger_irq(unsigned int irq)
 {
        struct irq_cfg *cfg = &irq_cfg[irq];
-       cpumask_t mask;
-       unsigned long flags;
-
-       spin_lock_irqsave(&vector_lock, flags);
-       cpus_clear(mask);
-       cpu_set(first_cpu(cfg->domain), mask);

-       send_IPI_mask(mask, cfg->vector);
-       spin_unlock_irqrestore(&vector_lock, flags);
+       send_IPI_self(cfg->vector);

        return 1;
 }